The present invention relates to improvements in the enhancing of nuclear magnetic resonance (NMR) imaging of a subject, e.g. organs of a patient.
X-rays have long been used to produce images of internal organs of a patient, the patient being positioned between a source of x-rays and a film sensitive to the rays. Where organs interfere with the passage, the film is less exposed and the resulting picture, upon development of the film, is an indication of the state of the organ.
More recently, another imaging technique has been developed, viz. nuclear magnetic resonance imaging. This avoids the harmful effects sometimes attending X-ray exposure. For improved imaging with x-rays, patients have been given enhancers prior to imaging, either orally or parenterally. After a predetermined time interval for distribution of the enhancer through the patient, the image has been taken. The time of good imaging is desirably as short as possible after taking the enhancer; on the other hand there is a decay in the effectiveness, so desirably the decay is relatively slow so as to provide a substantial time interval during which imaging can be done. The present invention relates to enhancers in NMR imaging.
Australian patent application 86 330/82 of July 22, 1982 and U.S. Pat. No. 4,647,447 (Gries, et al.), issued Mar. 3, 1987, disclose the use as an NMR image enhancer of a complex salt, preferably the gadolinium chelate of diethylenetriaminetetraacetic acid, plus an amine. From the data reported therein these appear to perform well. However, this compound is highly ionic and is rapidly excreted by the kidneys, making the timing of the injection extremely critical. Furthermore, there is virtually no uptake by any solid organ, such as the heart, pancreas or liver. Moreover, an amine is also required.